Postcode is a portmanteau, which is popular in many English-speaking countries. (known in various countries as a post code, postal code, or ZIP code) is a series of letters and/or digits appended to a postal address for the purpose of sorting mail.

There are a number of colloquial terms for postcode.
postal code
The general term is used directly in Canada.
ZIP code
The standard term in the United States and the Philippines; ZIP is an acronym for Zone Improvement Plan.
PIN code / pincode
The standard term in India; PIN is an acronym for Postal Index Number.

Postcodes were first introduced in the Union of Soviet Socialist Republics in December 1932, but the system was abandoned in 1939. The next country to introduce postal codes was Germany in 1941, followed by Argentina in 1958, the United Kingdom in 1959, the United States in 1963 and Switzerland in 1964.

In February 2005, 117 of the 190 member countries of the Universal Postal Union had postal code systems. Countries that do not have national systems include Ireland and Panama. Although Hong Kong and Macau are now Special Administrative Regions of China, each maintains its own long-established postal system, which does not utilize postal codes for domestic mail, and no postal codes are assigned to Hong Kong and Macau. Mail between Hong Kong, Macau and mainland China is treated as international.